Principles of RF superconductivity

Instructors: Sergey Belomestnykh and Wencan Xu, Brookhaven National Laboratory

One-week course at USPAS 2013, Durham, NC

January 14-18, 2013

Purpose and Audience

This one-week graduate level course covers physics and technology application of RF superconductivity and its application to contemporary particle accelerators. The course will address fundamentals of RF superconductivity, types of superconducting RF (SRF) accelerating structures, phenomena limiting performance of those, beam-cavity interactions issues specific to superconducting cavities, cavity fabrication, preparation and testing, different approaches to designing SRF systems and engineering of superconducting cavity cryomodules. The course is intended for graduate students pursuing accelerator physics and graduate engineers and physicists who want to familiarize themselves with superconducting RF systems.

Prerequisites

Classical mechanics, thermodynamics, electrodynamics, and physical or engineering mathematics, all at entrance graduate level.

It is the responsibility of the student to ensure that he or she meets the course prerequisites or has equivalent experience.

Objectives

Upon completion of this course, the students are expected to understand the physics underlying RF superconductivity and its application to accelerators, the advantages and limitations of SRF technology. The aim is to provide students with ideas and approaches enabling them to evaluate and solve problems related to application of superconducting cavities to accelerators, and actively participate in engineering of SRF systems for various accelerators.

Instruction Method

This course includes a series of about 15 lectures during morning and afternoon sessions. In addition, there will be computer lab and exercise sessions. Homework problems will be assigned. Homework will be graded and answers provided in the exercise sessions. There will be a final exam at the conclusion of the course.

Course Content

The course will include a brief introduction of the basic concepts of microwave cavities and transmission lines. This will be followed by in-depth coverage of principles of RF superconductivity. Different types of SRF structures will be introduced. Then it will cover field emission, multipacting and beam-cavity interaction issues in accelerators. Following that we will discuss cavity fabrication and preparation techniques, and cavity testing. Finally, we will address issues related to engineering of the SRF systems and components: cryostats, cavities, input couplers, higher order mode couplers and loads, and frequency tuners. A brief overview of the most important challenges in RF superconductivity will conclude the course.

Textbook

(to be provided by USPAS) “RF Superconductivity for Accelerators”, by H. Padamsee, J. Knobloch, and T. Hays, John Wiley & Sons, 2nd edition (2008).

Reading Requirements

It is recommended that students re-familiarize themselves with the fundamentals of electrodynamics at the level of

“Fields and Waves in Communication Electronics“ (Chapters 1 through 11) by S. Ramo, J. R. Whinnery, and T. Van Duzer, John Wiley & Sons, 3rd edition (1994)

“Classical Electrodynamics” (Chapters 1 through 8) by J. D. Jackson, John Wiley & Sons, 3rd edition (1999).

Additional suggested reference material (not provided by USPAS):

“Handbook of Accelerator Physics and Engineering”, edited by A. W. Chao and M. Tigner, World Scientific, 3rd print (2006)

“RF Superconductivity: Science, Technology, and Applications,” by H. Padamsee, Wiley-VCH (2009).

"Introduction to Wakefields and Wake Potentials" by P. B. Wilson, SLAC-PUB-4547 (1989).

"High Energy Electron Linacs: Application to Storage Ring RF Systems and Linear Colliders" by P. B. Wilson, SLAC-PUB-2884 (1982).

"Fundamental-Mode RF Design in e+e- Storage Ring Factories" by P. B. Wilson, SLAC-PUB-6062 (1993).

Credit Requirements

Students will be evaluated based on the following performances: final exam (40%), homework assignments and class participation (35%), Computer Lab project (25%).

Computer Lab and Codes

During the Computer Lab sessions students will be working on a project using computer codes ABCI and SUPERFISH. The codes will be installed on the USPAS computers. The other codes that will be available on the USPAS computers are: MathCAD, MATLAB, Microsoft Office.
Please keep in mind that commercial software (MathCAD, MATLAB, Microsoft Office) will not be available for installation on students' laptops due to licensing issues. Students will have to use USPAS computers to have access to these software if they do not have it. However, it will be sufficient to use Open Office or Google Docs instead although it may be a bit less convenient.
ABCI code and documentation can be downloaded from the ABCI Home Page. It is available in Windows and Linux versions.
SUPERFISH can be downloaded from the LANL Accelerator Code Group Download Area for Poisson Superfish. It has only Windows version.

Computer Lab Project

Computer Lab project description

SUPERFISH input file

ABCI input file

Lecture Notes and Homework Problems

Monday

Lecture 1: Introduction: advantages and limitations of SRF technology

Lecture 2: Fundamentals of RF & microwave engineering

Lecture 3: Basic concepts of RF superconductivity: RF losses and related figures of merits, Q vs. E

Monday homework problems

Tuesday

Lecture 4 - this is the lecture from Monday